The relation of open magnetic structures to solar wind flow

Levine, Randolph H.

doi:10.1029/ja083ia09p04193

Cited by 35 publications

(15 citation statements)

References 19 publications

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“…The bottom panels include the same open field regions, together with the projections of coronal field lines intercepting the low‐latitude source surface at the equator, and 20°N and 20°S latitudes. Levine [1978] used similar displays to describe the sources of the upstream solar wind, assuming that the coronal field lines reaching the source surface equator represent effective stream tubes. The heavy line is the projection of the source surface neutral line that separates solar wind streams of opposite magnetic polarity.…”

Section: Modeled Coronal Hole Sourcesmentioning

confidence: 99%

“…Over 20 years ago, Levine [1978, 1982] and others had demonstrated the ability of potential field source surface models of the coronal magnetic field to reproduce coronal hole foot points at the photosphere seen in He10830 angstrom images throughout the solar cycle, as well as to explain some high‐speed streams detected at Earth during the disk passage of certain coronal hole features. Since then, Wang and Sheeley [1990a, 1994] have undertaken a number of studies of the long‐term solar magnetic field control of coronal holes and solar wind using potential field source surface models based on Mt.…”

Section: Introductionmentioning

confidence: 99%

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Solar cycle changes in coronal holes and space weather cycles

et al. 2002

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[1] Potential field source surface models of the coronal magnetic field, based on Mt. Wilson Observatory synoptic magnetograms, are used to infer the coronal hole sources of low-heliolatitude solar wind over approximately the last three solar cycles. Related key parameters like interplanetary magnetic field and bulk velocity are also calculated. The results illustrate how the evolving contribution of the polar hole sources relative to that from low-latitude and midlatitude active region hole sources can explain solar magnetic field control of long-term interplanetary variations. In particular, the enduring consistent magnetogram record and continuous model displays produce a useful overview of the solar control of interplanetary cycles and trends that affect space weather.

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Section: Modeled Coronal Hole Sourcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Solar cycle changes in coronal holes and space weather cycles

et al. 2002

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“…Beyond this source surface, the field is assumed to be purely radial. The approximations implicit in this procedure have been discussed in detail elsewhere (Altschuler and Newkirk, 1969;Schatten, Wilcox, and Ness, 1969;Levine, 1978); they include the use of 27-day Carrington maps (which limit the temporal resolution), the neglect of possible coronal currents (which would distort the fields), and the use of a constant-radius source surface (which affects the size of the derived open field regions, i.e., coronal holes). Wang and Sheeley (1990a) used the same source-surface model with the slightly different radius R s = 2.5 Rp, which provides agreement with the observed sizes of the polar holes near sunspot minimum (Sheeley, Wang, and Harvey, 1989) and with the observed sector polarity of the interplanetary field (Hoeksema, 1984).…”

Section: Concepts Of the Modelmentioning

confidence: 99%

Magnetic field configurations associated with fast solar wind

Sheeley

Wang

1991

Sol Phys

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In this paper, we consider the implications of the observed inverse correlation between solar wind speed at Earth and the expansion rate of the Sun-Earth flux tube as it passes through the corona. We find that the coronal expansion rate depends critically on the large-scale photospheric field distribution around the footpoint of the flux tube, with the smallest expansions occurring in tubes that are rooted near a local minimum in the field. This suggests that the fastest wind streams originate from regions where large coronal holes are about to break apart and from the facing edges of adjacent like-polarity holes, whose field lines converge as they transit the corona. These ideas lead to the following predictions:(1) Weak holes and fragmentary holes can be sources of very fast wind.(2) Fast wind with steep latitudinal gradients may be generated where the field lines from the polar hole and a lower-latitude hole of like polarity converge to form a mid-latitude 'apex'.(3) The fastest polar wind should occur shortly after sunspot maximum, when trailing-polarity flux converges onto the poles and begins to establish the new polar fields.

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“…We construct synoptic maps of SWS computed by the CAT technique in the same 13 Carrington rotations as the ones for the RBR. Levine, Altschuler, and Harvey (1977), Levine (1978), and Wang and Sheeley (1990) pointed out that the solar wind speed observed near the Earth shows a negative correlation with the expansion rate of coronal magnetic flux tubes near the Sun. This relation has been studied extensively by Wang et al (1997, and references therein).…”

Section: Introductionmentioning

confidence: 96%

Correlation between Expansion Rate of the Coronal Magnetic Field and Solar Wind Speed in a Solar Activity Cycle

et al. 2005

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Thirteen synoptic maps of expansion rate of the coronal magnetic field (CMF; RBR) calculated by the so-called 'potential model' are constructed for 13 Carrington rotations from the maximum phase of solar activity cycle 22 through the maximum phase of cycle 23. Similar 13 synoptic maps of solar wind speed (SWS) estimated by interplanetary scintillation observations are constructed for the same 13 Carrington rotations as the ones for the RBR. The correlation diagrams between the RBR and the SWS are plotted with the data of these 13 synoptic maps. It is found that the correlation is negative and high in this time period. It is further found that the linear correlation is improved if the data are classified into two groups by the magnitude of radial component of photospheric magnetic field, |B pho r |; group 1, 0.0 G |B pho r | < 17.8 G and group 2, 17.8 G |B pho r |. There exists a strong negative correlation between the RBR and the SWS for the group 1 in contrast with a weak negative correlation for the group 2. Group 1 has a double peak in the density distribution of data points in the correlation diagram; a sharp peak for high-speed solar wind and a low peak for low-speed solar wind. These two peaks are located just on the axis of maximum variance of data points in the correlation diagram. This result suggests that the solar wind consists of two major components and both the highspeed and the low-speed winds emanating from weak photospheric magnetic regions are accelerated by the same mechanism in the course of solar activity cycle. It is also pointed out that the SWS can be estimated by the RBR of group 1 with an empirical formula obtained in this paper during the entire solar activity cycle.

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The relation of open magnetic structures to solar wind flow

Cited by 35 publications

References 19 publications

Solar cycle changes in coronal holes and space weather cycles

Solar cycle changes in coronal holes and space weather cycles

Magnetic field configurations associated with fast solar wind

Correlation between Expansion Rate of the Coronal Magnetic Field and Solar Wind Speed in a Solar Activity Cycle

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